The present invention relates generally to bandages for holding and positioning devices inserted into arteries. More particularly, the present invention concerns a one-piece assembly for supporting an arterial catheter against dislocation, keeping the incision site clear, and bandaging the area.
In the healing arts there are two different kinds of probes which are inserted into the blood system of a patient: intravenous probes and arterial catheters. These different kinds of probes take their names from the different parts of the human circulation system into which they are inserted, namely arteries and veins. However, the differences between these two kinds of probes are considerably more significant than the mere difference between the names.
Intravenous probes are used for administration of medications, involuntary feeding, and blood transfusions. Arterial catheters are not, however, used for those functions. Quite apart from intravenous probes, arterial catheters are used to provide attending medical staff with important information concerning the patient's circulatory system and its functioning.
For example, arterial catheters help doctors to determine whether a patient is in either a hypertensive crisis or hypotensive crisis during surgery, as well as after surgery. In addition, these arterial catheters allow blood sampling for various purposes, including determination of the blood gas value.
Another important use for arterial catheters is to monitor the positive pulsating pressure in the artery which is dynamic and which is generated by the patient's heart. That positive pulsating pressure creates a different operating environment for the arterial catheter as contrasted to the intravenous probe. More particularly, the intravenous probe operates in veins where the pressure is static and is caused primarily by gravity.
The pressure monitored in the arterial catheter is used to regulate all infusion of blood and drugs administered to the patient. Generally, the arterial catheter is used during serious medical situations such as during the pendency of surgery, during post-operative recovery, and during residence in an intensive care unit of a hospital.
Besides the difference between the location and function of arterial catheters as compared to intravenous probes, the arterial catheters actually have a different construction than do the intravenous probes. Some intravenous probes (called "butterflies") are rigid needles which are very short and which are used in delicate veins. In contrast, the large majority of arterial catheters in use today are of the flexible type. For example, the arterial catheter generally is a two part system having an inner stylet surrounded by a flexible outer sheath made of polytetrafluoroethylene, such as Teflon. The stylet allows the catheter to puncture the skin and enter an artery or vein. Once the catheter has been inserted, the stylet is removed leaving the outer sheath in place within the artery. When the flexible tube which penetrates into the artery has a pressure sensor that is thus placed in intimate association with the blood stream, the catheter can be used to measure blood pressure. The intravenous probe, on the other hand, is typically a rigid needle inserted into a vein.
Since arterial catheters are flexible and since they communicate with a pressure monitoring system, kinks, crimps, and bends in the line can cause changes in the pressure reading. In medical parlance such changes in pressure readings are referred to as positional sensitivity of the arterial catheter. Positional sensitivity occurs more often in an arterial line than in a venous line because of the different character of the musculature of an artery in comparison to a vein. To reduce positional sensitivity the catheter should remain as central to the arterial wall as possible due to the dynamic construction and dilation of the arterial wall in response to the blood flow demands of a patient's body.
Positional sensitivity of the arterial catheter leads to another difference between the arterial catheter and an intravenous probe: the arterial catheter must be capable of rotation about its longitudinal axis, whereas the intravenous probe needs no such rotatability. Rotation of the arterial catheter permits the monitoring equipment to determine whether positional sensitivity is interfering with the clearest readings. Accordingly, bandaging the arterial catheter to the patient involves different requirements than does the intravenous probe.
The different locations of the arteries and the veins in human anatomy are also a factor in the application of arterial catheters to the patient. Generally speaking, arteries are positioned deep within the limbs of a patient whereas veins are located near the skin surface. To insert an arterial catheter, it becomes necessary to locate one of the few areas of the body where arteries pass close to the skin surface. For example, the radial artery which passes through the forearm is near the skin surface along the wrist, the brachial artery which passes through the upper arm is near the skin surface at the crease of the elbow, the femoral artery which passes through the thigh is near the skin surface at the groin, and the dorsalis pedis artery of the foot is near the skin surface at the ankle. Thus, it will be observed that the places where arterial catheters can be inserted are not only limited by are located at awkward areas where limbs also articulate. As a result there are special problems associated with arterial catheters which are not encountered with intravenous probes.
When an arterial catheter has been inserted, there are several highly desirable characteristics that an anchor bandage should provide. The entrance of the catheter into the skin should be subject to visual inspection. The anchor bandage should be rigid so that the arterial catheter will be held in a secure, fixed relationship to the patient. The anchor bandage should provide reliable, prompt application. And, the anchor bandage should be sterile.
In the past, the normal procedure for insertion of an arterial catheter has been to clean and disinfect the skin area around the intended insertion point. Then an incision is made to insert the arterial catheter in the selected artery. With the catheter in place, additional skin penetrations are necessary to suture the arterial catheter into its proper position and location. Thereafter gauze pads are applied to draw drainage from the wound away from the wound and tape is applied to secure the gauze in place. Since the area of cannulation is often located at one of the patient's joints, it is often necessary to secure the limb to a board or other rigid member to prevent inadvertent movement that could cause a positional affect on readings taken from the arterial catheter.
The procedure heretofore used has numerous problems and disadvantages associated therewith. For example, the arterial catheter often is highly positional. In addition, the site of catheter entry into the patient is often obscured and not visible. Typically the procedure to finish the procedure once the arterial catheter has been placed in the artery can consume 3 to 10 minutes or more, depending on the experience of the staff person who installs the catheter. And furthermore, since the arterial catheter is often inserted under conditions which demand great haste, it is not always dressed with sterile materials. In addition, there are a number of different items which must be stocked in order to effect the bandaging of an arterial catheter, all of which require precious storage space.
From the foregoing discussion, it will be apparent that there is a considerable difference between bandages for arterial catheters as compared to intravenous probes. That difference indicates that devices for applying and bandaging of intravenous probes have little or no relevance to arterial anchor bandages. In fact, no prior art arterial anchor bandages are known.
There are of course numerous devices for holding and protecting intravenous probes. For example, it is known to provide a transparent enclosure with a mounting sheet and to use that assembly to enclose an intravenous probe. See for example U.S. Pat. No. 3,900,026 issued to Wagner and U.S. Pat. No. 3,782,377 issued to Rychlik. Other intravenous devices are disclosed in U.S. Pat. No. 2,266,230 issued to Mazzei et al, U.S. Pat. No. 3,288,137 issued to Lund, U.S. Pat. No. 3,782,378 issued to Page, U.S. Pat. No. 4,324,237 issued to Buttaravoli, and U.S. Pat. No. 4,502,477 issued to Lewis. As emphasized, structures associated with intravenous probes are not transferable to use with arterial catheters.